图示零件是冷挤压加工的常见产品。由于受到许用变形程度、模具使用寿命等因素的限制,因而欲想进行一次正挤压成形,则应对于该类零件的杆径d、挤压余料高度h_1、锥角a以及过渡圆角半径R、r等尺寸有一定的成形极限。一、杆部直径杆径d过小,变形程度增加;过大,中心层产生附加拉应力,导致内部产生裂纹。因 Pictured parts are common cold extrusion products. Due to the degree of allowable deformation, mold life and other factors, so want to make a positive extrusion, then the parts of the rod diameter d, extrusion residue height h_1, taper angle a and transition fillet Radius R, r and other dimensions have a certain forming limit. First, the rod diameter rod diameter d is too small, increasing the degree of deformation; too large, the center layer of additional tensile stress, resulting in internal cracks. because